Changes in magnetic resonance mammography due to hormone replacement therapy

BACKGROUND: The aim of the present article is to investigate effects of hormone replacement therapy (HRT) on contrast medium enhancement patterns in postmenopausal patients during magnetic resonance mammography (MRM). MATERIALS AND METHODS: Two hundred and fifteen patients receiving hormonal medication were divided into four groups: 150 patients with 1 MRM during HRT (group A), 13 patients with 2 MRMs under HRT (group B), 30 patients with 1 MRM during HRT and 1 MRM after HRT withdrawal (group C), and 22 women with 1 MRM after HRT withdrawal (group D). Dynamic MRM was performed at 1.5 Tesla. Signal intensity changes were characterized by five time curves: minimal enhancement (type I), weak continuous enhancement (type II), strong continuous enhancement (type III), and a steep initial slope followed by a plateau phenomenon (type IV) or a washout effect (type V). RESULTS: Of all 193 patients under HRT (group A + group B + group C), 60 patients (31.1%) showed curve type I, 88 patients (45.6%) showed type II and 45 patients (23.3%) showed type III. There were significant differences to 52 patients after HRT withdrawal (group C + group D) (P < 0.0001), with 42 patients (80.8%) for curve type I, 8 patients (15.4%) for type II, and 2 patients (3.8%) for type III. In both MRM sessions in group B, 69% of the patients showed identical curve types without significant differences (P = 0.375). In group C, 28 of 30 patients (93%) dropped to lower curve types with significant differences in curve types during and after HRT (P < 0.0001). CONCLUSION: The majority of patients receiving postmenopausal HRT showed bilateral symmetrical, continuous enhancement without evidence of a plateau phenomenon or a washout effect due to HRT in MRM. Hormonal effects could be proven and were reproducible and reversible

Determining the Rotational Orientation of Directional Deep Brain Stimulation Leads Employing Flat-Panel Computed Tomography

BACKGROUND: Directional deep brain stimulation (DBS) constitutes an emerging technology that allows selective stimulation of target structures via partitioned electrode contacts. In order to effectively perform target-tailored stimulation, knowledge of the rotational orientation of the segmented leads is imperative. OBJECTIVE: To develop a universally applicable and reliable method for determination of lead orientation angles in DBS using flat-panel computed tomography (fpCT). METHODS: A binary template of directional leads DB-2202-30 (Boston Scientific, Natick, Massachusetts) and 6170 (Abbott, Plano, Texas) was imported into the 2-dimensional raw data set of a conventional fpCT scan. The template was aligned with andmanually rotated around the predetermined lead trajectory. The overall orientation of the segmented lead can be deduced by transferring position and orientation of the lead orientation marker into the 3-dimensional volume. Accuracy of the method was investigated by two raters in a phantom study. RESULTS: Accuracy were 5.4 degrees +/- 4.1 degrees (range: 0.4 degrees-11.9 degrees) for rater 1 and 5.2 degrees +/- 3.0 degrees (range: 0.3 degrees-10.2 degrees) for rater 2, when investigating DB-2202-30. For 6170 observed deviations were 2.5 degrees +/- 1.7 degrees (range: 0.2 degrees-5.2 degrees) and 4.3 degrees +/- 3.6 degrees (range: 0.2 degrees-11.2 degrees) for raters 1 and 2, respectively. CONCLUSION: fpCT imaging constitutes a precise and accurate means to determine the rotational orientation of directional leads. The approach is universally transferable to different electrode designs as the template can easily be adjusted to the electrodes'specific measures. The approach is independent from polar implantation angles owing to fpCTand methodological features